Disturbing influence detecting element



G.' Mus-'FLY msTURB. NGIHFLUEncE bETEcTme :i

2 Sheets-Sheet' 1 sued Nov. 13, 1944 t. 17, G, MUFFLY .2,412,742

DISTURBING INFLUENCE DETECTINGELEMENT -Filed Nov. 13, i944 2 Slieetsheet 2 GARY ,MUFFLY Patented i?, 1946 nmLUaNoa ELEMENT Gary Mumy, Penn Township, nAllegheny County, i Pa., assignor to- Gulf Research & Development nrsr'onenvo Company, Pittsburgh,

' Delaware ns'rncrmo Pa., a corporation of' Application Noyelober 13,4 1944, serial No.. 553,251

7 Claims. (Qi. 177-3542) This invention pertains toda device for indicating a disturbance in the normal conditions surrounding the mechanism and in particular one which indicates when the disturbance has reached its maximum value. magnetic, electric, acousticor any condition which may be converted intoan electric ind.

cation. A f

In the operation of detecting mechanismsifor lcontrol operations it is often of insuicient value to make the detector respond merely at a certain held value. It is quiteoften essential .that the device indicate the peak `of a disturbance which iii-st increases and then recedes. This invention has for one of its principalwobjects the provision ci a device for indicating the time of maximum value oi' a disturbance, that is. it gives an indication just as the disturbing inluencebegins rto recede. l

Another object of the-invention4 is to produce a device which indicates lthe moment of maxi--v mum disturbance electrically, regardless of the nature of the disturbing inuence Aitself,'in order that a remote indicatormay be used.

One manifestation of the maximum of 4a dis-y turbance is that or closest approach of a'passing vehicle, vessel, or other disturbing inuence. As

The disturbance may be vPil \ effects are most common and will be described,

a disturbing influence approaches a point, its effect iirst increases, then reaches a maximum and then decreases. This is still true if the disturb- Yance passes somedistance from the point. It is generally true whether thedisturbance be magnetic, electric, electromagnetic, optical, acoustic,

l thermal or any other. In order to carry outthis invention it is only .necessary that the influence be convertible into an'4 electrical indication, that is, by means of a magnetic detector, tuned'electric circuit, photocell, sound detectozg'pyrometer, and other such known' devices.

One example of the application of thedevice is in submarine Warfare. In detecting devices for use with mines it `isla problem to obtain .an indication of the correct vtime for ring sothat the mine will be set oi at the opportune moment to inflict the greatest damage. It must gol oi near the vessel or vehicle in' order to cause appreciable damage. device for ring an influence mine atthe optimum instant in :order to inflict maximum de-` struction to a passing vessel.- The instant of closest approach is the ideal' firing time and it is accordingly an object achieved by my invention to provide a device for automatically accomplishing this aim.

If a detector element in a mine is made sensi- This invention concerns a tive enough to indicate or trip on very small targets, then very large ones may actuate the mine from such a largel distance that no damage will be' done to the target. Very large or very4 strongly magnetic vessels maythen4 actuateV the mine so'` itfires as much as several hundred feet before the ship gets to the mine. Thus a further object of this inventionis to provide means for indicating `the closest approach of a target regardless of its physical size or the magnitude of the dis' turbance producedvby it.

Inuencemines usually operate to lre when the influence attains anarbitrarily chosen value,

-or aftery the lapse of an arbitrarily chosen time from initial detection. The present invention is designed to give aring signal, or alternatively to actually do the firing, when the iniiuence reaches its greatest or peak value. By picking the peak response regardless of its magnitude, the

The means forobtaining' the response, that is,

- the detecting element itself may be entirely electrical or partly mechanical. Various types of influences may beused, but magnetic or acoustic herein, but this invention is not meant to be limited to the above. 4 a It is furthermore evidenty that the invention may be'used to indicate the instant at which an iniluence reaches its minimum as well as maximum.

c In the accompanying drawings Ihave shown and will make the understandingof the more complicated device easier. InFig. 1 a magnetized compass needle i is suspended on slender wire filaments 2 and 3. The' wire should be so fine that it will `have little eect ,on the sensitivity of the needle. The needlewll line up approximately with'the earths eld if the restoring force of wires 2 and 3 is small. However, if a vehicle approaches, the direction of the airain target is'A sure to be caught/at about its nearest DOnt of approach.`

neldwill be slightly disturbed and the needle will,` viiuldlbe 'coupled through la llarge changeposition.` If the needle moves clockwise, togrid-24;ofanamplier`tube 2 ,willgcontact' rods Il at each end of the needle', and'grid Vleak"2isi'1ouldbe lar hu` dszi'rwill `be contacted if-it moves countei'- `theslowest'tluctu 1 kwis `Since thecontact ro'ds 4 and. 5 mustarbef f n v tolthevtips of the magnetic need1e'foi-" high sensitivity, `and 'the position of vthe `'needle cannot-be predicted accurately, it is necessary us 4sp'ceialfneans to keep the needle nozrnallyl` a n ed ybetween the contacts independentlyfof :1'0 tion of the needle. This is accomplished ery ei'ziblespring 6i which attaches to the nee e and `to the strip?, which spaces andi'n` ultes-thegcontact rods. Rods d also serve stof 'upport'strip 'Ifrom a damping ring '8'wh'ichgis1| pr erably'loating in a viscous fluid 9.i The fluid d pingringshould be Vdesigned so thatthe elat ely=-strong-magnetic for'ceswill movethe in dily when the needle is deectedfagain'st 31 and `38 "on `th une., pairtpf contact rods,` but it should provide f manner.l "Latches y 'damping 'of therring alone when the needlev 1 closedftemporar tweeriltherods and only the'weak spring closedfwithi'nfa acting to-mov'erth'e ring. If these ,conditonsn l a4 sfled,r both sets of contacts will hemadepassage offa .target even `'though the f magnetic field is unidirectionalfi .When :c

icm-occurs as the target comes y1.1y .fthe4 1 1 strike one pair ot contacts antidrug p ping freingalong. with-it; When th y. ached, howeventhe damping:

emainat the maximum deection j s damping, while the needle will drop very shortly strike the other pair'ofA l en., i

On grapprcacri of a target theinmal `dciiec-V f 1o mayI occur ineither direction, and Vit may cur at toc great a distance. Therefore the two y nitactf'closures are used to actuate *separate ir uits, both `of which mustbe afctuatedjbefore h` e'vvlll re. In the device of Fig. 1,'lock-in' 5 fa'nd `Ii are tripped Separately ,byl the Y ojco act closures, and the'iheavier contacts l2 losedihytherelaysare connected in seriesw'ith ,detonatorfl andhattery i4 .to set o the mine faft'elrfbothfrelays have tripped; Latches I 5 hold*` the Arelays in so that the .first one actuated `'will A ainiclosed while thermagnet swingsoverfto Vond'set ofcontacts.V e e electrical circuit to the needle is through Contacts 5 are connected together and 50- ug fspring B to wire 3, which is insulated mthe magnetic' needle. Contacts 4 connect conductive surface on ring 8 whichjwill A j e nsmitzthe current through the liquid to `a. `sub ergedelectrodc I6; Obviously liquid 9 must 55 .reasonablygood electrical conductor. 'The A .cY made ofv an insulating material ora metal A[tivi insulating bushings for the leadv wires. '.,Conacts (fand 5 may be spaced 'bymeans of insulating beads 'I vl' of glass or the like; 60

Fig Zwillustrates an improved electronic` cirv y n 4 ovidingthe desired firing actioniwith-f he useof delicate contacts. Here the de4 :i vice 2lfmay'bea t magnetic .detector di lo's'ed lfor example in Vacquier'mi-` eri lNo. 403,455, or it may-'ne ensuit-J phone or otherI `influence-receliiyer l n A, `leiisefto whichthe mine is putlfilis, associate equipment 22z-includes virhatever` Y r] other deviceslar'e necessaryltoigive output ,whichiiluctuatcsiin"response` j "r..example,with amicropho uallir` be f used-here,1 this. i, v C.. .Output mvrfpetticni@ a g received. They iluctuations i.'

ing the ring cycle.

aeia'rea the rise of voltage is large, condenser 23 can charge up rapidly through diode 48, since it is no longer subject only to the slight charging current that can pass through leak'25. However, condenser 23 can never charge to a voltage greater than the maximum voltage swing of de vice 22. For example, if the output of detector 22 reaches a peak swing of 30 volts, these 30 volts, at the moment the peak lis reached, may be dvided as 29.5 voltsof change across the condenser 23 and 0.5 volt of change across the diode 48 and grid 24. If this peak signal should be held artihas another advantage when used with magnetic mines of the type we have developed. This particular mine uses a detector thatv generates a steady voltage roughly proportional to the steady eld value applied to it. If this mine is disturbed by enemy action, it may be suddenly subjected to iicially, the condenser 23 would. ultimately be charged to the full increment of 30 volts, and the 0.5 volt increment would disappear from the grid 24 and the diodes. However, if resistor 26 and condenser 23 have large values as specied, this might take a matter of several minutes. Ordinarily, the peak signals are followed rapidly by decreases so that this tendency to drift back t0 equilibrium may be-ignored. When the crest of the voltage rise is just passed, the signal voltage begins to drop. The voltage on grid 24 begins to dropimmediately Condenser 23 keeps its charge now because the voltage on the diodes again falls within the zoneof negligible current. For example, when the signal voltage drops backv from I7the 30-volt peak in the illustration above to 29.5 volts, the charge of 29.5 volts on condenser 23 is exactly neutralized by this momentary signal value, and the grid and diode signal voltage is momentarily zero. Soon grid 24 drops below its normal value even though the signal is still near its maximum, as, for example, to minus 0.2 volt when the signal voltage drops from the 29.5 volts mentioned above to 29.3 volts. At some such point of slightly negative signal on grid 24, relay 30 trips in the reverse direction, complet- If the safety switch 52 in the detonator circuit is open so that the mine does not blow up at this point, the receding signal will drive the voltage at grid 24 downward until a, substantial current ows through diode 49 and discharges condenser 23 so that it returns approximately to its initial state. To continue our example, if the signal drops to zero, the grid and `diode voltage may be driven to about minus 0.5

volt, while condenser 23 discharges rapidly through diode 49. The remainingsignal voltage of 29.3 volts across the condenser will drop rap` idly to 0.5,volt or so, depending on the cutoff point of the diode, and thereafter drift. more and more gradually to equilibrium'.

An upward swing of signal voltage tends, upon its removal, to leave the grid 24 with a residual negative voltage. This condition isqdescribed as blocking in the art, and would be serious for large swings except that the reversed limiter diode 49 limits the amount of this residual voltage to a very small value. Regardless of the direction or strength of signals, 4the residual voltage is held within close limits. The blocking or reversal eiect does not occur before the swing that causes it begins to recede. l One can see that the ring point will not be exactly at the signalpeak. The second relay closure tends to be delayed by the finite recession required to' eiiect the synthetic voltage reversal at grid 24. On the other hand, the resistance-capacitance coupling circuits tend to distort the fluctuations and advance` the peaks. These two factors can be balanced against one another p to give optimum firing conditions on the average target.

It should be noted that the diode arrangement a new value of field and consequently a new detector voltage. Consequently grid 24 will be thrown far from its normal value of voltage if the diodes are omitted. Condenser 23 still provides for return of the grid voltage to normal but its time constant with leak 26 is long enough so that several minutes may elapse before recovery is satisfactory for operation of the mine. If, however, the diodes are in the circuit, grid 24 will not change voltage as much in the rst place and will also come back rapidly into the operating range. Only the last part of therecovery will occur with the normal long time constant. The total recovery time is cut to a mere fraction by this circuit.

Incase the bias of tube 25 is of a suitable value, diode 48 may be omitted because grid 24 will then `draw current and take over its function. Often,

`the magnetic needle with respectI to strip 'l of Fig.

1 and the diodes limit the magnitude of the volt- -age swing on grid 24 in Fig. 2.- The trip points of either device are moved along with the indication. When either limit is reached and the indication persists and gets stronger after the de;

. vice trips in one direction, the second trip point is dragged along with theindication, so to speak. This shifting of the tripping points with respect to the initial indication of the influence device is necessary to get the desired trip action.

The terms trip or "tripping as used in this specification may be dened for purposes of this invention as meaning to actuate something so that it stays actuated either irreversibly, or reversibly upon deliberate action. In most cases one would want reversibility upon deliberate action so that the device may be reset. Such a function may be performed by a latch, but for purposes of this invention a"1atch or latchable means as claimed may comprise any equivalent means for carrying out the function of a, latch, i. e., actuating so that it stays actuated except for deliberate resetting. Such devices for purposes of this invention may also be electrical or magnetic in character as well as mechanical, for example, the latching relays shown may be replaced by a thyratron or gaseous discharge tube which when tripped stays tripped until reset as is well known, or the relay armature may press a snap-over mechanism which would stay snapped, or the device may drop weights, or a magnetic relayfmay be used to hold the deflection by magnetic* attraction. lSuch expedients may be employed instead of a mechanical latch for purposes of this invention as will be apparent to one skilled in the art.

What I claim is:

1. A device for indicating the proximity of a moving object comprising a detector providing a unitary response to inuence of the object, latchable means actuated by a small increment of the response, and latchable means actuated by a. small decrease in the same response.

2. A device for signaling the proty ci a from a received maximum influence.

3. A device for indicating the instant of closeest approach of a ydisturbing body comprising a.-

detector of the disturbance, said detector actuating a latchable mechanism when excited in one direction, said detector also actuating a latchable mechanism when excited in the opposite direction, and indicators responsive to the latching of both mechanisms and of both in sequence.

4. A device for indicating the instant of closest approach of a disturbing body, comprising a. detector of the disturbance having a wide range of response, a sensitive latchable indicator connected thereto which has a much smaller lower threshold of response actuated by an effect in one direction of said detector, a similar sensitive latchable indicator actuated by an effect in the other direction, and means for indicating the consecutive operation of said latching means;

5. A device for indicatingv the proximity of a disturbance'producing moving object, comprising means for electrically ldetecting the disturbance, means for impressing the Voltage on a,

series connected capacitor and resistor having a long time constant, diodes biased beyond cutoi and shunting said resistor in opposite directions, amplifying means connected across said resistor,v the last tube of the amplier constituting emana one arm of a bridge circuit, and an indicator showing the direction of unbalance of said bridge circuit.

6. A device Afor indicating the maximum or minimum ofa disturbing inucnce comprising means for converting the influence into an electrical voltage and having connected thereto a capacity-resistance circuit whose time constant is long compared with the disturbance, the resistance being shunted with diodes in opposite di- `rections and biased beyond cutoff, an amplifier connected across the resistance, and means for indicating the direction of the ampliiied signal.

7. A device for indicating the proximity of a conveyance comprising a magnetic eld indicator responsive to a wide range of magnetic eld values, a latchable -device set to operate when the iield indication `shifts a predetermined small amount 'in one sense from the normal value, a second latchable device set-to `operate when thel eld indication` shifts a like predetermined l amount in the opposite sense from the normal A GARY MUFFLY. 

